Advances in wireless technologies have allowed network operators to improve the features and services that can be provided to end users. New techniques, such as power control and link quality based physical channel-assignment, enable tighter frequency reuse and improve spectral efficiency. As a result, these features strongly influence a network operator's ability to provide adequate quality of service to a large number of users. In sparse reuse deployments that are limited by the number of channels rather than interference levels, channels may be assigned randomly to end users. However, channel assignment techniques that rely on interference measurements have recently been employed to achieve better spectral efficiency through tighter reuse. The benefit of interference-based channel assignment, e.g., assignment to the lowest interference channel, is that users are more likely to encounter good quality on this channel and as a result are more likely to maintain sufficient quality with reduced transmit powers. Such power control allows the interference in the network to be reduced and therefore, allows higher system capacity to be achieved.
When power control techniques are employed, minimum interference based channel assignment may not maximize power control gains. For instance, in IS-136 networks where discontinuous transmission is unavailable on the downlinks, performance may be improved by packing users onto idle slots of active carrier frequencies to minimize the amount of network-wide interference. In addition, practical systems typically have limited dynamic range that can impact channel assignment decisions. Finally, there may be transmit power variation constraints between time slots on a carrier frequency. In order to guarantee sufficient quality to end users, the carrier's transmit power may be dictated by the worst quality user, thereby limiting power control gains. In such cases, good users on a carrier may experience much higher quality than necessary since there are users with worse quality on the carrier who require higher transmit powers.